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Everything you ever wanted to know about the AW4

I did - but that's written with aw4 replacement in mind, not swapping an aw4 in. Since your harnesses don't have the plugs anyways it's pretty moot - and the harnesses from a 92 won't fit a 96, so it doesn't gain you much if anything. That plus the fact that the 92 is an unknown condition trans and the 89 you know the condition of means I would save the money. Maybe buy the TCU and brake light switch off him, with pigtails, but that's about it.
 
Ok thanx, Will do then on just getting the pigtails, brake light switch, and TCU. Now will I be able to use his 92 TCU with my 89 Tranny? Will his TCU recognize my Tranny by just splicing in the different pigtails?
Sorry for so many questions this will be my first auto swap and I just wanna make sure I get everything right. And will I also need to get the flexplate off of his 92 since my donor is a renix 4.0?
 
Yes to all - I forgot to mention the flexplate :eek:
 
Yes, but what year jeep is it going in? It shouldn't really matter between those years but may change things a little.
 
Yes, but what year jeep is it going in? It shouldn't really matter between those years but may change things a little.

Wouldn't a 92 be OBDI and a 96 OBDII? I'm thinking it should work, but would throw a check engine light with a P0700 code. I'm not positive on the connector, but I think that didn't change until 97/98.

I'm home wih the flu, so the brain's a little fuzzy right now.

-Chris
 
I'm doing an aw4 conversion in my 94 grand Cherokee and have a 96 trans. From wiring diagrams show the tcu connectors all being the same as the 92. But u found a 96 computer today so it doesn't matter now.
 
Wouldn't a 92 be OBDI and a 96 OBDII? I'm thinking it should work, but would throw a check engine light with a P0700 code. I'm not positive on the connector, but I think that didn't change until 97/98.

I'm home wih the flu, so the brain's a little fuzzy right now.

-Chris
I'm not sure. 96 is a bastard year as you know, it's got the old style TCU, transmission, NSS, and wiring harness but is OBDII... I think it'll be fine. MIGHT set a CEL.

Since it's going in a ZJ anyways, all bets are off. The PCM on the ZJ controls the stock transmission and probably won't be happy about not being able to do its thing anymore, and I don't have enough experience with the ZJ electronics to tell if it will set a CEL because of it or not. Any 91-96 XJ TCU will work with any 87-97 AW4 for the purposes of this swap though. Go any later than a 96 TCU and you'll definitely get some CELs (if you hook the TCU CCD bus up to the ZJ CCD bus, you don't have to and I probably wouldn't) and the 98 and later AW4s have a different ISS/OSS setup, but any of the others are fair game as long as you can manage to bolt it all up / the spline counts match, etc.

Another thing I might worry about is the shifter cable setup and the flexplate, I am not sure if the bolt pattern for the AW4 torque converter is the same as the bolt pattern for the ZJ stock torque converter or not. If it is you're all set, if it isn't, you might have to do some redrilling or something, unless you can verify that the CPS slots in the ZJ stock flexplate are the same as the slots in the XJ 91-01 flexplate (which I would think they are, but can't guarantee.)

I'll do some parts catalog cross-ref checking in a bit and see if I can find anything else that might cause a problem.

edit: the flexplate is in fact different between the AW4 and the chryco auto for the ZJ. I can't tell you how different, but looking at pics on rockauto it doesn't look good. Both are 4 bolt but appear to be different hole diameters and possibly bolt circle diameter, and the chryco flexplate has 4 large holes punched in it in between them to either lighten the flexplate or (more likely) increase its flexibility. The 93 ZJ was available with the AW4 and uses the same flexplate as the XJ, so you may simply be able to bolt on an XJ flexplate, but I'm not entirely sure.
 
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I was led to believe the zjs shared the cumputrr but it turned out mine has a separate computer for is 42re, go figure. So now I just have to tie into the old harness for the tips and key switch power and such and should be good to go. I hope.
 
The trans is all in and all the linkage is hooked up correctly so I'll it needs is its brain to run it. I'm doing a right up on the conversion as I go on another site.
 
If you don't care about running it the "proper" way you can control it easily enough with an RADesigns shifter or a rotary switch and some wiring. It's really simple, and pretty foolproof to drive, it's like a manual without having to deal with a third pedal or worry about stalling.
 
Was actually contemplating the rad design shifter. But my wife will also be driving this jeep on occasion and is very forgetful of things so I'm going to make sure it get installed right so she doesn't have to worry about it. I'll probrbly wire in solenoid 2 on a switch so I can lockout 2 for crawling.
 
Was actually contemplating the rad design shifter. But my wife will also be driving this jeep on occasion and is very forgetful of things so I'm going to make sure it get installed right so she doesn't have to worry about it. I'll probrbly wire in solenoid 2 on a switch so I can lockout 2 for crawling.

For locking out 2nd, you could set it up using a 2-pole momentary switch and a relay. When the vehicle is first turned on it would default to normal, hit the switch one way to disconnect the solenoid, and the other to go back to normal. That way you can't forget and it'll be normal when your wife takes it. Let me see if I can draw something up real quick.
 
So here is a drawing of my brief brain storm on that idea.

The relay starts out unenergized and the solenoid and tcu are connected normally. Hitting the momentary switch to ground the coil will engage the relay, and after that the ground continues to be through the solenoid (not enough nearly power to engage it though). Hitting the momentary switch to + will de-energize the coil and let things return to normal. The only downside is that this will briefly send enough power to the solenoid and the tranny might shift into second briefly. The relay pin numbers are from memory, should double check those.

solenoid_relay.jpg
 
What do you mean by that? High or low voltage? If you mean temperature, it should definitely be cold at all times... if it gets hot you should probably replace it!

According to my 98 FSM, the brake light switch input on the TCU should be grounded during normal driving, and 12 volts when braking. It is parasitically pulled high by the shifter interlock solenoid (the solenoid that is attached to the shifter mechanism and keeps you from shifting out of park unless your foot is on the brakes.) I would wire the brake light sense input on the TCU like this:
* 1k ohm resistor from brake light sense input to 12 volt ignition switched power
* brake light switch (normally closed - this is for failsafe reasons, with a normally closed switch, if the switch breaks, the TCU thinks the brakes are always on and the brake lights are constantly illuminated) from brake light sense input to ground.

That is based off info in my 98 FSM, which means it probably applies to 97-01 vehicles and TCUs. I will see if I can find my older FSMs and compare, they might be different.

If all else fails - you can experiment and find what the TCU expects by running a wire to the brake light sense input on the TCU, then driving at highway speeds. Once the torque converter lockup engages, tap the wire against a ground, if the RPMs jump, the TCU sees a ground as indicating brake pedal depressed. Then tap the wire against a 12 volt source (I'd probably use the cig lighter center terminal), if the RPMs jump, it sees 12 volts as indicating brake application.
 
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